just like the title say's, only happened after unplugged the map sensor the went to start it, and the cooling fan cuts on as soon as it fires up and dies and white smoke comes out the tb, any idea's thanks for the help

here's some background: 97 2.4L
Problem is after I rebuilt the top end [nothing wrong with the motor just burned a quart of oil in between oil changes], machined cylinder head, new timing chain and guides and tensioner new water pump, new lifter and etc. now she won’t stay running. go to start it up it cranks up and run for 2-4 seconds and then die, if you try to start right after it dies engine just rotates, if you wait 7-10 minutes it'll crank back up and do it all over again. things I have notice, new spark plugs have heavy black deposits on them and right before it die it has a little back fire out of the TB and it also backfires a little while the engine is rotating but not cranking. Change fuel pump, junk yard fpr, check compression 145-150, check spark, new battery, and 4 gals. of gas in tank, scanned for codes "nothing," theft light is solid don't believe it's the problem did security relearn many times already, all sensors are the same on the car except the used egr valve I bought bc I lost the original doing the build.

Although your compression isn't "too" bad, I would have expected a bit more. Based on what you've had apart, I would suspect cam timing - especially the intake camshaft. I've never had one of those engines apart to try to give any specific help on that, but it certainly sounds like the first thing I would expect. Even being 1 tooth out may make enough of a difference to cause that - and if there's a camshaft position sensor, then the computer may figure out that things aren't right, and bring things to a halt.
Just my guess strictly from a theoretical standpoint...
John

thanks for the theory and it does have a cps and i thought it was something dealing with time too so i re-timed the engine a total of 3 times and each time the engine did the same thing but who know's it might be off a tooth, do anyone know how to check this??